1. Field of the Invention
This invention relates to an oil pump for separate lubrication for supplying a lubricating oil to an automobile, a motor bicycle, a snowmobile, etc., and particularly relates to a compact reversible oil pump suitable for the snowmobile.
2. Description of the Background Art
The present applicant proposed a reversible oil pump in Japanese Patent Application No. 10-64286. This reversible oil pump is a lubricating oil pump with the rotation of an engine as a pump driving source and can be applied to a 2-cycle engine such as a snowmobile, etc. having no back gear. In this reversible oil pump, a cylinder is rotatably arranged in a cylindrical space formed in a pump body, and a worm wheel engaged with a driving worm is integrally formed in a plunger arranged in a pump chamber of this cylinder such that the plunger can freely go in and out of the pump chamber. A lead cam arranged in the worm wheel comes in press contact with a discharging amount setting cam. The worm wheel and the cylinder are engaged with each other with play.
A pump action is taken by making the plunger go in and out of the pump chamber of the cylinder. An oil is discharged or sucked from an inlet-outlet path communicated with the pump chamber and opened to a cylinder circumferential face to an outlet hole or an inlet hole arranged in the pump body. Since the worm wheel and the cylinder are engaged with each other with play, the relation of a rotating position of the cylinder and going in and out timings of the pump chamber of the cylinder is changed by a rotating direction of the worm wheel, and the oil is sucked from the inlet hole of the pump body and is discharged from the outlet hole in the rotation in any direction. Namely, the pump is set to be reversibly rotated.
In the above reversible oil pump, the plunger goes in and out of the pump chamber from an arranging side of the driving worm. Accordingly, the plunger is arranged between the outlet hole of the pump body and the driving worm so that a problem exists in that the outlet hole is separated from the driving worm and the pump is large-sized.
In a proposal described in Japanese Laid-Open (Kokai) Patent No. 8-270890 with respect to a nipple of the oil pump for separate lubrication, an engaging claw is arranged in a portion in which a nipple body made of synthetic resin is inserted into the pump body. The engaging claw is engaged with a step difference portion of an outlet port of the pump body. A noncircular inner circumferential face of a direction holding member engaged with the pump body is fitted to a noncircular outer circumferential face of the nipple body to stop rotation of the nipple body.
In the above nipple of the oil pump for separate lubrication, the step difference portion engaged with the engaging claw is arranged in the outlet port of the pump body so that boring processing is required and manufacturing cost is increased. Further, since a portion inserted into a hose for supplying the oil to the engine is thin, a problem exists in that this portion is easily broken when this portion is formed by synthetic resin.